Dog-racing opponents narrowly lost seven years ago when they tried to end greyhound racing in Massachusetts. They made a tactical error in 2006.

Now, theyre at it again.

“Third times a charm,” said Kara Holmquist, spokeswoman for the Massachusetts Society for the Prevention of Cruelty to Animals.

That remains to be seen, of course, but advocates are confident voters will agree to shut down Massachusetts 72-year-old greyhound racing industry. The Committee to Protect Dogs this past week submitted enough signatures to put the question on the statewide ballot in November 2008.

Massachusetts is among 16 states that allow dog racing, and its two dog tracks, Raynham-Taunton Greyhound Park and Wonderland Greyhound Park in Revere, have fought off previous ballot efforts that threatened to put them out of business.

Dog-racing opponents say greyhounds are confined to small cages for long periods and during races risk serious injuries such as broken legs and heart attacks. They argue the health of dogs should outweigh the entertainment value of racing.

They collected state data from the two tracks showing that since 2002, there have been 728 greyhound injuries, 80 percent of which were broken bones. A greyhound named Starz Voice was euthanized after a June 25 elbow fracture at Raynham Park, for example.

“Its time to stop this cruelty to dogs,” said Wayne Pacelle, president and chief executive of the Humane Society of the United States, which is among the groups supporting the initiative.

The Humane Society of the United States contributed $100,000 to the ballot committee last month, Pacelle said. Thats far more than what the organization spent in Massachusetts in the past, he said.

Track owners, who deny allegations of abuse, defeated ballot bids in 2000 and in 2006. Seven years ago, the ballot question to ban greyhound racing was defeated by a margin of 48.6 percent to 46.7 percent.

Last year, Raynham Park owner George Carney argued that the ballot question didnt pass constitutional muster. The states highest court agreed, keeping the question off the 2006 ballot. The Supreme Judicial Court ruled that it was unfair to voters to combine the dog-racing proposal with measures to expand criminal penalties for dog fighting and the neglect or abuse of dogs.

Carney, Raynham Park manager Gary Temple, and Wonderland general manager Richard Dalton did not return several calls each to comment.

State Rep. David Flynn, D-Bridgewater, has argued that closing the dog tracks would have a huge economic impact in the state. The Raynham track provides 600 jobs and is the largest private employer in his district. Wonderland employs another 600 people.

“It would be an awful blow,” said Flynn spokesman Tim Taylor. “Most of these jobs carry insurance. Theyre jobs that cant be replicated.”

The greyhound racing fan base is dwindling, all sides agree. The tracks have been looking for revenue through expanded gambling, lobbying unsuccessfully for legislative approval to install thousands of slot machines to boost revenue.

Wonderland had a 46 percent gross revenue decline in live betting from 2005 to 2006.